The following invention relates to a modified BNC connector for connecting an active probe to an electronic device such as an oscilloscope utilizing a standard BNC connection without the need for auxiliary power cables and the like.
BNC connectors are typically used on electronic instruments where a 50 ohm transmission line, connected to a probe or other peripheral device, is required to be connected to the front panel of the instrument. The probe termination is typically the male portion of a BNC connector, and the female portion of the BNC connector is situated on the front panel of the instrument.
Electronic instruments such as oscilloscopes now typically employ active probes, that is probes which include active circuitry, requiring positive and negative power supplies. With active probes the instrument may make various voltages and signals available at the probe which greatly increase the instrument's measuring capability. In order to provide the probe with these capabilities, it has been necessary in the past to connect an auxiliary cable from the probe's active circuitry, usually contained within a housing, to a location on the instrument where access may be gained to power supply components. This is awkward and inefficient because the auxiliary cable must typically be connected at the rear of the chassis, while the analog input line is connected through the conventional BNC connector on the front panel of the instrument. Moreover, it is necessary in the design of new instruments which use active probes, to retain the basic BNC input connection on the front of the instrument for those users who do not need active probes. In this way, older probes which lack the active circuitry could be used with newer model test instruments because the BNC connecting jacks would remain compatible with the older probes.